An apparatus and a method of the type set forth at the outset are known from US 2007/0121100 A1. Described therein is a measurement apparatus for measuring spectacles, having a first measurement station in which there is an illumination device and a first image capture device with a camera serving to capture the permanent markings on a spectacle lens. In a further measurement station, arranged at a distance from the first measurement station, the measurement apparatus has a further image capture device with a camera serving to measure the refractive power of spectacle lenses. In the measurement apparatus, spectacles to be measured have to be displaced in a referenced manner between the measurement stations by way of a receptacle mechanism.
DE 1 238 690 B1 describes a lensmeter with a spectacle mount for measuring the vertex power of spectacle lenses which are held in the frame of spectacles.
U.S. Pat. No. 8,081,840 B2 discloses an apparatus for checking an optical element that is transparent to light or that reflects light, having an illumination device and a camera. In the apparatus, the optical element to be tested is arranged between the illumination device and the camera. Then, a multiplicity of patterns which run through a phase shift are provided with the aid of the illumination device. Subsequently, an individual image is calculated from the phase-shifted patterns, and optical data of the optical element is derived from the individual image.
U.S. Pat. No. 5,307,141 describes an apparatus for determining the refractive power distribution of spectacle lenses in a pair of spectacles. However, permanent markings of the spectacle lenses that define a local, body-inherent coordinate system are not captured in this case.
WO 95/22748 A1 and U.S. Pat. No. 7,486,389 B2 disclose an apparatus for determining the refractive power distribution of spectacle lenses in which spectacle lenses are measured without a spectacle frame.
U.S. Pat. No. 5,973,772 A specifies a system for determining the refractive power distribution of spectacle lenses in spectacles, the system having a first measurement station for determining the form of the frame and containing a further measurement station, arranged separately from the first measurement station, serving to determine optical characteristics of spectacle lenses when these have not yet been received in spectacles.
In order to facilitate in-focus vision for a spectacle wearer, the spectacle lenses must be correctly positioned and aligned in relation to the eyes of the spectacle wearer in the frame of a pair of spectacles. In principle, the correct alignment and positioning is required in all spectacle lenses. The correct alignment and positioning of the spectacle lens is of particular importance in the case of individualized optical spectacle lens designs and/or in the case of progressive lenses. Progressive lenses allow spectacle wearers in-focus vision in different use situations, e.g., at different distances, by changing the viewing direction only, without this requiring a relatively large accommodation success of the eyes in the process. Individual lenses and/or progressive lenses have one or more reference points, e.g., a distance reference point and a near reference point, the orientation of which, depending on the use situation, must be adapted to the location of the pupils of the eyes of a spectacle wearer.
In technical terms, the near reference point and the distance reference point of progressive lenses are also referred to as near construction point and distance construction point. A definition of these points is provided in Chapters 5.13 and 5.14 of the EN ISO 13666:1998 standard, the entirety of which is referred to herewith and the content of which is incorporated into this application.
Ideal vision with progressive lenses presumes that the progressive lenses held in a spectacle frame are positioned in front of the eyes of the spectacle wearer in such a way that the orientation of the distance reference point and the orientation of the near reference point conform to the viewing directions of the spectacle wearer when looking into the distance and when looking up close. Therefore, according to the specifications in Chapter 7 of the DIN EN ISO 8980-2:2004 standard, progressive spectacle lenses must be provided with at least two permanent markings. According to the aforementioned standard, these at least two markings must exist on a progressive spectacle lens with a spacing of 34 mm and must be arranged symmetrically to a vertical plane through the fitting point or the prism reference point. These two markings define a local, body-inherent coordinate system for the spectacle lens. These markings can be used to reconstruct in a spectacle lens both the lens horizontal and reference points, such as the distance and near reference points, the so-called fitting point defined in Chapter 5.24 of the EN ISO 13 666:1998 standard or the prism reference point defined in Chapter 14.2.12 of the EN ISO 13 666:1998 standard.
Pursuant to the EN ISO 13 666:1998 standard, the fitting point is a point on the front surface of a spectacle lens or spectacle lens semi-finished product, which, according to the specification from the manufacturer, should serve as reference point for positioning the spectacle lens in front of the eyes.
In the case of uncut spectacle lenses, which an optician obtains from a spectacle lens producer for a spectacle wearer on account of a refraction deficit determined for the spectacle wearer, the orientation of these points with the aforementioned markings is specified implicitly. That is to say, an optician can establish the distance and near reference point, the fitting point and the prism reference point on the basis of the aforementioned markings or on the basis of figures that are printed on the spectacle lenses and referenced to the markings. Pursuant to the EN ISO 13 666:1998 standard, the prism reference point is the point specified by a manufacturer on the front surface of a progressive spectacle lens or a progressive spectacle lens semi-finished product at which the prismatic effects of the completed lens have to be determined.
This makes it easier for an optician to align the uncut spectacle lens correctly prior to grinding and then insert it into a spectacle frame in the correct position, such that the spectacle wearer is provided with optimal vision.
This disclosure understands individual data of spectacles to mean, in particular, so-called spectacle-wearer-specific fitting data of the spectacles, i.e., data from the group of refractive power of a spectacle lens of the spectacles, refractive power distribution of a spectacle lens of the spectacles, the position of the near reference point and the position of the distance reference point of a spectacle lens of the spectacles in a coordinate system that is referenced to the spectacles and hence, indirectly, to a spectacle wearer who wears these spectacles as well. This disclosure understands individual data of spectacles to mean also the orientation of the at least two markings on a progressive spectacle lens according to the DIN EN ISO 8980-2:2004 standard, in a coordinate system that is referenced to the spectacles in which the progressive lens is arranged.